【Question】

I have a text file called readings, it has the following data in it:

-10,3NW,15cm,4:38

5,15SW,8mm,2:8

8,8ENE,2mm,:25

-5,0,7cm,1

-3,0,3mm

 

From the first position, they are temperature, speed, precipitation and time (hours and minutes).

I want to split the string with tokens = line.split(":") only if the fourth token exists. My code for splitting the strings without doing any splits with the delimiter : is:

 

   try {

        input = new BufferedReader(new FileReader("readings.txt"));

 

        line = input.readLine();

        while (line != null) {

            tokens = line.split(",");

 

            temperature = Integer.parseInt(tokens[0].trim());

 

            tokens[1] = tokens[1].trim();

            separation = firstNonNumericPosition(tokens[1]);

 

 

 

 

            if (separation == 0 || (separation < 0 && Integer.parseInt(tokens[1]) != 0)) {

                speed = -1;

            } else {

                if (separation < 0) {

                    speed = 0;

                    direction = "";

                } else {

                    numeric = tokens[1].substring(0, separation);

                    speed = Integer.parseInt(numeric.trim());

                    direction = tokens[1].substring(separation).trim();

                }

 

                if (tokens.length > 2) {

                    tokens[2] = tokens[2].trim();

                    separation = firstNonNumericPosition(tokens[2]);

                    if (separation <= 0) {

                        precipitation = -1;

                    } else {

                        numeric = tokens[2].substring(0, separation);

                        precipitation = Integer.parseInt(numeric.trim());

                        unit = tokens[2].substring(separation).trim();

                    }

                } else {

                    precipitation = 0;

                    unit = "";

                }

 

            }

 

 

            if (speed < 0 || precipitation < 0) {

                System.out.println("Error in input:" + line);

            } else {

                readings[size] = new Reading(temperature, speed, direction,

                        precipitation, unit.equalsIgnoreCase("cm"));

                size++;

            }

 

 

 

 

            line = input.readLine();

        }

 

        input.close();

 

 

 

    } catch (NumberFormatException ex) {

        System.out.println(ex.getMessage());

    } catch (IOException ioe) {

        System.out.println(ioe.getMessage());

    } catch (ArrayIndexOutOfBoundsException ar){

        System.out.println(ar.getMessage());

}

 

I tried using this logic but it gave an ArrayIndexOutOfBoundException of 3.

 

if(tokens.length > 3) {

   tokens = line.split(":");

   hours =Integer.parseInt(tokens[3].trim());

   minutes =Integer.parseInt(tokens[4].trim());

}

 

How is it possible to split it if the fourth token exists?

 

【Answer】

Your target: To structurize the text data into a five-column 2D table. Problem description: The 4^th column is irregular and you need to split it into two columns by comma. This will involve order-based calculation and structured computation. Without further requirements, we can handle it in SPL (Structured Process Language). The code is simple and easy to understand.

	A
1	=file("d:\\source.txt").import@c()
2	=A1.new(#1:Temperature,   #2:speed, #3:precipitation,  (t=#4.array(":")).m(1):hours   ,t.m(2):minutes)

A1: Read in source.txt as a 4-column table sequence.

 

A2: Split the 4^th column into two columns by the comma to generate a new 2D table consisting of 5 fields – temperature, speed, precipitation, hours, and minutes.

 

The SPL script can be easily integrated into a Java application. See How to Call an SPL Script in Java.